Mystery surrounds the disappearance of two Chinese women last seen at the Giant's Causeway eight weeks ago.

The tourists were on a trip to the local beauty spot as they toured the scenic north coast.

The alarm was raised when 30-year-old Ni Xiaofang and 26-year-old Ni Zhiling did not return to their tour bus on Tuesday, July 29.

Police first issued an appeal when they became concerned for the pair's welfare on August 2.

Vanished Ni Xiaofang is described as approximately 5ft 2ins, of slim build and with short dark hair.

When last seen she was wearing a yellow jumper, blue jeans and flip flops.

Ni Zhiling is also around 5ft 2ins, of slim build and was wearing a pink jumper, blue jeans and flip flops when last seen.

Yesterday, two months since they were last spotted in Northern Ireland, police reissued an appeal for information.

Detective Chief Inspector Catherine Magee said both women had been spotted since they disappeared.

She said: "There have been credible sightings of both women in the Republic of Ireland, specifically in the Carrick-on-Shannon area, but we need to establish that these women are safe and well and ensure they have not come to harm or are in a dangerous situation."

Police have asked them or anyone who knows of their whereabouts to contact them on the non-emergency number 101.

Local DUP councillor Robert McIlroy said it was a very "concerning" situation.

He said: "Certainly, it's a situation that if anyone knows or has seen them they should pass on that information.

"It's just unbelievable. Eight weeks is a long time and at the end of the day there must be family somewhere who are very concerned about this situation."

The PSNI currently has 19 registered missing people on its website – some who have been missing for more than 20 years.

Among those never found are Malaysian student Chang Swee Chaun, who has been missing since 1991.

He was studying at the University of Ulster at Coleraine and had an address in Portstewart.

The young student went missing after attending a disco at the Londonderry Hotel, Portrush, on March 15, 1991.

He was last seen on March 16, 1991, in Main Street in the town.

Chi Dan, who police describe as an oriental female teenager believed to be between 16 and 18 years old, was last seen in the Magherane Road area of Randalstown on May 15, 2008.

Martin Kelly (21) from Holywood was last seen enjoying drinks with friends at Pat's Bar in the Docks area of Belfast.

He was captured on CCTV at 7.15pm on New Year's Day 2006 but has not been seen since despite public appeals.

Meanwhile, 49-year-old Samuel Campbell was last seen cycling near Broughshane 45 minutes after he left his home in Kells on New Year's Day 2012.

His bicycle was found by the seafront near Glenarm, Co Antrim, on January 3.